Facial nerve examination and anatomy and neuroanatomy and physiology and course. Applied anatomy and Bell's palsy.

1. Facial nerve
examination

2. Content
Introduction
Anatomy
Clinical Examination
Applied aspect

3. Facial nerve
SeventhCN- mixednerve.
Nerve ofsecond brachial arch
Nerve offacialexpression.

4. The facialnerve (CN VII) – motor + sensory
Parasympatheticsecretory fibers
submandibular,sublingualsalivaryglands
lacrimal gland
mucous membranes ofOral andnasal cavities.
Sensory functions:
Taste
sensation(eardrumandexternalauditorycanal)

5. InfranuclearNuclear
Four
components
Supranuclear
Pyramidal and
extrapyramidal
ANATOMY

6. SUPRAN UCLEAR AN ATO M Y
Has specificareason thecerebral
cortex.
Facial pyramidal fibers begin
Itis representedaccordingto thepart it
supplieson the face.

7. Path of voluntary facialexpressions
(Pyramidal)
Contralateral precentralgyrus arecarried
through corticobulbar tract (pyramidal)
Internal Capsule
Midbrain
Cross over to theopposite side
Motor Facialnerve nucleusin Pons.
DeJong's The Neurologic Examination, 6th Edition

8. EXTRAPYRAMIDAL SYSTEM
Consist of basal ganglia and the descending motor projections other
thanthefibersofthepyramidor cortico-bulbar tracts.
Extrapyramidal system, involves diffuse axonal connections
between multiple regions including the basal ganglia, hypothalamus,
andmotor cortex.

9. Facial Nerve has 4 nuclei
(lower pons)
1. Motor nucleus
2. Sup salivolacrimatory
nucleus (parasympathetic)
3. Nucleus of tractus
solitarius (gustatory)
4. Spinal tract nucleus
(sensory)
Nuclear / Intra-axial Anatomy
DeJong's The Neurologic Examination, 6th Edition

10. Motor nucleus fibres
Ventrolateral pontine tegmentum
Floor of fourth ventricle forming
facial colliculus
Fibers then course anterolaterally to exit lateral
brainstem at pontomedullary junction

11. Sup salivolacrimatory nucleus (parasympathetic)
Nucleus of tractus solitarius (gustatory)
Spinal tract nucleus (sensory)
NERVOUS INTERMEDIUS
DeJong's The Neurologic Examination, 6th Edition

13.  The facialnerve leaves the brainstem in two roots
MOTOR ROOT (70%)
NERVOUS INTERMEDIUS (30%)

14. Extra-axial
course
Emerge from lateralbrainstemat root exit
zone on pontomedullary junctionjust
caudalto theroots of CN V
DeJong's The Neurologic Examination, 6th Edition

15. Cisternal segment
Has 2 roots atthe exit
Larger motor root anteriorly
Smallersensory nervus
intermedius posteriorly
CN8 exits brainstemposterior toCNVII
These nerves resemblethenerve roots ofthespinalcord in that
theyaredevoidofepineuriumbutcoveredinpiamater andbathedin
CSF

16. Intrapetrous course ofthefacialnerve hastwo portions:
(a) intheinternalauditory canal
(b) inthefacialcanalor Fallopean aqueduct
The internalauditory segmentis 7 to 8 mmin length

17. At theentranceto theinternal auditorycanal(IAC)
The facialnerveatthispointliesin closeproximityto theanterior inferior
cerebellarartery (AICA)

19. In itscourse through thefacialcanalthenerve hasfour segments:
1) Labyrinthine
II) Horizontal or tympanic
III) Pyramidal
IV)Mastoid

20. The labyrinthine segment
lies laterally between the
cochlea and vestibule, toward
the medial wall of the
tympanic cavity
It extends from the internal auditory canal to the geniculate
ganglion. (3–5 mm)

21. The nerve turns abruptly and
runs horizontallyfor about1
cm(horizontal or
tympanic segment)
Turns backwardandarches
downward behindthe
tympanic cavity.
Extends from the geniculate
ganglion to the second turn of
thefacial nerve External genu & geniculate ganglion

22. The tympanic nerve segment is covered by athin bony sheath.

23. The pyramidal segment joins thehorizontal and
mastoid segments,andgivesoffthebranchto the stapedius
muscle.
The mastoid segment (13–15 mm)
extends from this point to the
stylomastoid foramen.

25. After exitingthestylomastoidforamen,thefacialnerve gives off
branches to
The posterior auricular
The posterior bellyofdigastric
The stylohyoid

26. Sensory
Greater sup.Petrosal nerve
Chorda tympani
Motor
Nerve to stapedius
Posterior auricular
Nerve to Diagastric
Nerve to stylohyoid
Muscles offacial expression
Branches

28. Final Innervation
Innervates the muscles of facial expression.

29. General Somatic Efferents

30. Parasympathetic fibres

31. Special Visceral Afferents or Sensations

32. CLINICAL EXAMINATION
Examination of the Motor Functions
Inspection-
• Facial asymmetry, nasolabial fold with forehead wrinkles,
movements during spontaneous facial expression
• Tone of the muscles of facial expression,
• Atrophy and fasciculations
• Abnormal muscle contractions and involuntary movements
• Spontaneous blinking for frequency and symmetry.

33. Clinical Examination of the facial nerve
Motor
 Frontalis,
 Corrugator Supercilii
 Orbicularis oculi
 Buccinator
 Orbicularis Oris
 Platysma

35. Testing of Facial Nerve Branches
 Testing the temporal branches of the facial nerve –
patient is asked to frown and wrinkle his or her forehead.
 Testing the Zygomatic branches of the facial nerve patient
is asked to close their eyes tightly
 Testing the buccal branches of the facial nerve
• Puff up cheeks (buccinator)
• Smile and show teeth (orbicularis oris)
• Tap with finger over each cheek to detect ease of air expulsion
on the affected side

36. Examination of Reflexes
Corneal Reflex
• Afferent limb of the reflex is mediated by CN V1, the efferent
limb by CN VII.

37. Stapedius reflex
• Nerve to stapedius muscle test
• Impedence audiometry can record the presence or absence of
stapedius muscle contraction to sound stimuli 70 to 100 db
above hearing threshold
• Absence reflex or a reflex less than half the amplitude is due to
a lesion proximal to stapedius nerve

39. Examination of Sensory Functions
Hypesthesia of posterior wall of the external auditory meatus in
proximal facial nerve lesions.
Taste on anterior two-thirds of the tongue-use four substances
for testing:
• Sucrose (sweet), sodium chloride (salty), quinine (bitter), and
citric acid (sour).
• Patient with a peripheral pattern of facial weakness has
impaired taste, the lesion is proximal to the junction with the
chorda tympani.

40. Examination of Secretory Functions
• Tear production may be quantitated with the Schirmer test.
• Lacrimal reflex is tearing, usually bilateral, caused by
stimulating the cornea.
• Nasolacrimal reflex is elicited by mechanical stimulation of the
nasal mucosa, or by chemical stimulation using irritating
substances such as ammonia.
• Abnormalities of salivation are usually suggested by the history.

41. Other important tests
1. Schirmer's Tear test
2. Nerve conduction andPotential Studies
3. CT /MRI

42. (1829):THE DISCOVERY
OF THE NERVE OF
FACIAL EXPRESSION
Sir Charles Bell (1829)
3 cases of facialparalysis due
to facialnerve trauma.

44. Causes of nerve palsy

45. Facial Weakness
Two types of neurogenic facial nerve weakness:
• Peripheral or lower motor neuron - result from a lesion
anywhere from the CN VII nucleus in the pons to the terminal
branches in the face.
• Central facial palsy (CFP) - due to a lesion involving the
supranuclear pathways before they synapse on the facial
nucleus.

46. Peripheral Facial Palsy
• There is flaccid weakness of all the muscles of facial expression
on the involved side, both upper and lower face, and the
paralysis is usually complete

47. • Palpebral fissure is open wider than normal, and there may be
inability to close the eye (lagophthalmos).
• Very mild PFP may produce only slower and less complete
blink on the involved side.
• Bell’s phenomenon- Attempting to close involved eye causes a
reflex upturning of the eyeball
• Levator sign of Dutemps and Céstan- Patient look down, then
close the eyes slowly; because the function of levator palpebrae
superioris is no longer counteracted by orbicularis oculi, upper
lid on the paralyzed side moves upward slightly.

48. • Negro’s sign- eyeball on the paralyzed side deviates outward
and elevates more than the normal one when the patient raises
her eyes.
• Bergara-Wartenberg sign- loss of the fine vibrations palpable
with the thumbs or fingertips resting lightly on the lids as the
patient tries to close the eyes as tightly as possible.
• Platysma sign of Babinski- asymmetric contraction of the
platysma, less on the involved side, when the mouth is opened

49. House-Brackmann grading system
Grade I - Normal
Grade II - Mild dysfunction, slight weakness on close inspection,
normal symmetry at rest
Grade III - Moderate dysfunction, obvious but not disfiguring
difference between sides, eye can be completely closed with effort
Grade IV - Moderately severe, normal tone at rest, obvious weakness
or asymmetry with movement, incomplete closure of eye
Grade V - Severe dysfunction, only barely perceptible motion,
asymmetry at rest
Grade VI - No movement

50. Facial Weakness of Central Origin
• Weakness of the lower face, with relative sparing of upper face
• Upper face is not necessarily completely spared, but it is always
involved to a lesser degree than the lower face.
• Lesion involving the corticobulbar fibers anywhere prior to
their synapse on the facial nerve nucleus will cause a CFP
• Lesions are most often in the cortex or internal capsule.

51. Upper Motor Neuron (UMN) Palsy

52. • There are two variations of CFP:
(a) Volitional, or voluntary- weakness more marked on
voluntary contraction, when patient is asked to smile or bare
her teeth.
• Result from a lesion involving either the cortical center in the
lower third of the pre-central gyrus that controls facial
movements, or the corticobulbar tract.
(b) Emotional, or mimetic. –Facial asymmetry more apparent
with spontaneous expression, as when laughing.
• Most commonly results from thalamic or striatocapsular lesions,
usually infarction, rarely with brainstem lesions

54. Facial Paralysis
UPPER MOTOR NEURON LOWERMOTOR NEURON
Lesions is above the pons. Lesions is in the pons or in the
pathway from pons to its exit.
Patient can make furrows on looking
upwards
Furrows are absent on looking
upwards of the affected side of
face.
Lower part of the face is involved on
the opposite side of the lesion.
The whole face and forehead
involved on the same side of the
lesion.
Isolated involment of this type is
rare.
It is invariably associated with
hemiplegia .
Isolated involment of this type is
common.
It may be associated with
hemiplegia .

55. Localization of Lesions Affecting Cranial
Nerve VII
 Supranuclear Lesions (Central Facial Palsy)
 Nuclear and Fascicular Lesions (Pontine Lesions)
 Peripheral FacialNerve Palsy

56. Nuclear Lesions
 May affecteither the nucleus of the facialnerve or its intrapontine axons
Ipsilateral Facialpalsy with
Abducens fascicleor nucleus
Paramedian Pontine Reticular Formation
(PPRF)
(paralysis of conjugategazeto the psilateral side)
Corticospinal tract (contralateral hemiplegia)

57. Abducens fascicleor nucleus

58. PERIPHERAL LESIONS

59. Lower motor lesion of Facial nerve
• Palsy +loss of taste sensation – in the canal
• Palsy +loss of taste +hyperacusis – just after entrance
into the canal
• All the above + loss of hearing – atthe internal
auditory meatus
• All the above + lateral rectus damage – cerebo
potine angleinvolvement Bell’s palsy.

60. Millard-Gubler Syndrome
Lesion located in the ventral pons that destroys the fasciclesof the facialand
abducens nerves and the corticospinal tract
Ipsilateral peripheral-type facial paralysis
Ipsilateral lateral rectus paralysis
(diplopia with failure to abduct
the ipsilateral eye)
Contralateral hemiplegia

61. Foville Syndrome
Lesion locatedinthepontinetegmentumthat destroys
thefascicleofthefacialnerve,thePPRF, andthe
corticospinal tract.
Ipsilateralperipheral-typefacial paralysis
Paralysisofconjugategazeto theside
ofthe lesion
Contralateral hemiplegia

62. Möbius syndrome
Möbius syndrome results from the
underdevelopmentoftheVI and VII
cranial nerves.
Loss offacialexpressions and
horizontal gaze.

63. Localization of Peripheral Facial
Nerve Palsy

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